One or more embodiments of the subject matter described herein relate to data communications and, more particularly, to data communications with a rail vehicle.
Rail vehicles may include multiple powered units, such as locomotives, that are mechanically coupled or linked together in a consist. The consist of powered units operates to provide tractive and/or braking efforts to propel and stop movement of the rail vehicle. The powered units in the consist may change the supplied tractive and/or braking efforts based on a data message that is communicated to the powered units. For example, the supplied tractive and/or braking efforts may be based on Positive Train Control (PTC) instructions or control information for an upcoming trip. The control information may be used by a software application, such as Trip Optimizer™ from General Electric Company, to determine the speed of the rail vehicle for various segments of an upcoming trip of the rail vehicle.
The data message having the information used to control the tractive and/or braking efforts may be communicated to the rail vehicle while the rail vehicle is moving. For example, wayside equipment may wirelessly transmit the data message to an antenna of the rail vehicle.
However, as the rail vehicles move relative to the wayside equipment, the wireless transmission of the data message is subject to several propagation problems. These problems include, but are not limited to, the existence of dead spots or low signal areas where little to no data message is transmitted but through which the rail vehicle travels, reduced transmission rates due to the need to re-transmit lost data, and the like. Additional problems associated with wireless transmission of data messages include atmospheric interference, mechanical failure of the receiving antenna, and the like.
A need exists for a system and method for communicating with a rail vehicle that avoids one or more of the above shortcomings.